3.4.1 Define local area network (LAN), wide area network (WAN), server and client.
A LAN is a local area network. This is a small network generally consisting on between 2 and 10 computers sharing a network, possibly a printer too. A WAN is a wide area network. These normally cover a relatively large geographical area. WAN’s normally consist of two or more LAN’s joined together. A server is a program that will manage the resources in the network. A client is a remote computer or software that accesses a server in a network.
3.4.2 Explain basic network topologies.
There are three basic network topologies, Bus, Ring and Star. Bus Networks have all computers connected to a central network cable. This layout is least reliable because a break in the cable causes the loss of network for all computers. However, it is the least expensive to set updue to the small amount of cable needed.
Ring networks function as bus networks except the beginning computer is connected to the end computer. This means that a single break in the cable would not break the entire network. If there are two breaks, half of the computers will still be networked. However, the cost in wiring is larger than in a bus network.
Star networks have all clients connected to a server, hub or switch in the center. They are more reliable than ring and bus networks as each computer is connected to the server. If one connection breaks, all the other computers will function normally.
However, these aren't the only types. Below can be seen some other examples. You could also join two completely different network topologies together and form a hybrid network.
3.4.3 Explain the hardware required in networking.
For wired Bus type topologies, cables (such as the current CAT5) are necessary. If the network is to connect to the internet, then a modem and router are also needed. The cable uses a special connector to provide a high bandwidth connection between computers, principally using the Ethernet protocol.
Microwave communications are used mostly for networking mobile phones, however; some wireless routers also use a microwave signal to transmit data between computers. Microwaves are used as they suffer from less interference than radio-waves, due to large exploitation of this earlier technology.
The fiber-optic cables is used in communications as it provides a larger bandwidth and lower signal to loss ratio than an electric communications cable. Furthermore; the fiber optic cable does not suffer from interference due to its use of the optical method of data transmission. However, fiber-optic cables are still very expensive to install; disruption is another problem involved in installing fiber-optic cables.
The router is used to connect two networks; in this case the LAN and the WAN (Internet). The router works by routing packets interchangeably from the LAN to the WAN and, au contraire, by reading the address on individual packets and accordingly routing the electrical signal.
A hub is a simple device which is placed in the center of a star topology. It is a simple, inexpensive device as it only repeats signals from all of its inputs to all of its outputs, without directing packets. For this reason, a hub causes many packet collisions, therefore the hub network is less efficient than a switch and works slower.
A switch directs packets from its inputs to the appropriate outputs, preventing packet collisions. Switch networks are more efficient than hub ne
tworks because many hub packets would be lost during normal operation, whereas, the switch prevents this problem by directing packets according to their address.
3.4.4 Define the terms “standard protocol”, “data integrity” and “data security” in the context of data transmission across a network.
Standard Protocol refers to the set of rules that data has to follow in order to be transmitted over a network.
Data Integrity refers to ensuring that the data does not change accidentally due to interference or other causes, or is lost whilst being transferred over a network.
Data Security ensures privacy of data being transmitted over the network. Encryption is a very effective method of ensuring data security.
3.4.5 Explain the software involved in networking.
In order for a PC to connect to the internet from home it is necessary to have loaded system software that enables the PC to receive and transmit data via the modem, which is in turn connected to a p
hone line.In order for a PC to connect to a LAN it needs to have the appropriate communications client software loaded.Communications software deals with protocols and data security, both for LANs and WANs and handles the need for both integrity and security of data
3.4.6 Describe suitable methods to ensure data integrity in the transmission of data.
Parity checks
The number of bits that are 1 are counted
An extra bit is added such that there is an even or odd number of bits in the whole number.
Using this method an error may be detected.
Checksum (BCC - Block Character Check)
Values of successive bytes are added together
The sum is transmitted
The sum is re-calculated by the receiver
If it is the same, then it is assumed that no errors have occurred
Error Correction
When errors in transmission are deteced they need to be corrected. The most common type of error correction is ARQ (automatic repeat request), re-sending continues until correct communication is ach
ieved. Some codes allow a small number of corrupt bits to be corrected without retransmission ( forward error correction ).
This shows that parity checks can be applied to each character, as we have seen, but also the same bit from a number of characters can also be checked.
The errors in parity intersect at the incorrect bit and it can be "flipped" to achieve correction.
3.4.7 Describe suitable methods to ensure data security.
Data security is concerned with preventing unauthorised access.
User login
This requires you to enter a login and password and is the main form of network security. Passwords should be set sensibly and at a regular time interval. Passwords should not be associated with the user and should be a random combination of letters and digits. Passwords are stored on the computer but are stored in encrypted format so that if they are located they cannot be read.
Data encryption
Another major security problem is the interception of data transmissions by an unauthorised third party. In order to avoid this, data is ecrypted when transmitted. This basically means that the data is scrambled at transmit time I.E. encrypted and then de-encrypted when it is received. If the data transmission is intercepted after encryption, it cannot be de-encrypted without the use of an encryption key.
Permission
As well as passwords to enable users to login, each user also has a set of permissions associated with their logon name or group. Some users, administrators or super-users, can look in any data file, change user passwords and delete any file on the system. Ordinary users can only access their own files and use specified resources such as printers and CD burners.
Firewall
A firewall is a device, or a piece of software that is placed between your computer and the rest of the network (where the hackers are). A firewall blocks unauthorised connections from being made to your computer or LAN. Normal data is allowed through the firewall (e.g. e-mails or web pages) but all other data is blocked.
3.4.8 Discuss the need for speed in data transmission, and how speed can be enhanced.
There is a need for speed because data transmission has to be efficientand fast; if the bandwidth reaches its limit it can overload and it'll become impossible to transmit data correctly.
You can assure speed in data transmission by compressing data. There are two types of data compression:
Lossy data compression: This type of compression removes the unnecessary data. It is mainly used in pictures, example: conversion of a picture from GIF to JPEG and conversion of an audio file from WAV to MP3. Example of how this works: imagine a picture with a blue sky, almost every pixel in that part of the picture has a different shade of blue even if the change from one shade to another is almost null; when you apply lossy compression it takes a number of different shades and turns them into an 'average' shade. It is a very efficient and smart type of data compression because you can't really notice the difference unless you zoom in on the picture. The main difference between this and lossless compression is that with lossy compression you can't get the original file back.
Lossless data compression: This type of compression allows you to recreate the original file. It involves breaking the original file into a smaller version while it is transmitted or stored in a way that when it reaches its destiny it can be put back together and used as before. Example of lossless data compression is when you zip an amount of files into a file (usually done with 7-zip).
Youtube Video Explaining Lossy and Lossless Compression in Images:
3.4.9 Discuss networking applications and the implications of networking for organizations, including internal communications, electronic mail, e-commerce, conferencing and distributed processing.
Networks allow different computers to access the same hardware, like a printer; it can also share programs, data, internet and intranet. All this can benefit the organizations economically and interactively, because by installing a network in an organization, less hardware will be needed and everyone can do their work in a more organized way.
Internal communications: Networks allow the sharing of data without physical contact; Electronic mail is the most commonly used to communicate in networks because it allows people to share files and message each other quickly.
Electronic mail:
Advantages: share files and message each other almost instantly; cheap; time zones don't interfere; no need to move from their seats
Disadvantages: Security issues; impersonal; misinterpretation of the email.
E-commerce:
Conferencing: is when two or more people communicate with each other in real time, using services like Skype or Messenger (video conferencing); this allows them to have conferences without actually being in the same place.
Video conferencing:
Advantages: no need to travelcheaper.
Disadvantages: there is no 'bonding' between the persons involved
Online calls:
Advantages: avoids costs; it's easier and sometimes it has better quality than telephones
Disadvantages: it's not globally used
Distributed processing: is when a task is distributed between different computers within a network, to make it quicker to process.
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3.4.1 Define local area network (LAN), wide area network (WAN), server and client.
A LAN is a local area network. This is a small network generally consisting on between 2 and 10 computers sharing a network, possibly a printer too. A WAN is a wide area network. These normally cover a relatively large geographical area. WAN’s normally consist of two or more LAN’s joined together. A server is a program that will manage the resources in the network. A client is a remote computer or software that accesses a server in a network.3.4.2 Explain basic network topologies.
There are three basic network topologies, Bus, Ring and Star.Bus Networks have all computers connected to a central network cable. This layout is least reliable because a break in the cable causes the loss of network for all computers. However, it is the least expensive to set updue to the small amount of cable needed.
Ring networks function as bus networks except the beginning computer is connected to the end computer. This means that a single break in the cable would not break the entire network. If there are two breaks, half of the computers will still be networked. However, the cost in wiring is larger than in a bus network.
Star networks have all clients connected to a server, hub or switch in the center. They are more reliable than ring and bus networks as each computer is connected to the server. If one connection breaks, all the other computers will function normally.
However, these aren't the only types. Below can be seen some other examples. You could also join two completely different network topologies together and form a hybrid network.
3.4.3 Explain the hardware required in networking.
For wired Bus type topologies, cables (such as the current CAT5) are necessary. If the network is to connect to the internet, then a modem and router are also needed. The cable uses a special connector to provide a high bandwidth connection between computers, principally using the Ethernet protocol.
Microwave communications are used mostly for networking mobile phones, however; some wireless routers also use a microwave signal to transmit data between computers. Microwaves are used as they suffer from less interference than radio-waves, due to large exploitation of this earlier technology.
The router is used to connect two networks; in this case the LAN and the WAN (Internet). The router works by routing packets interchangeably from the LAN to the WAN and, au contraire, by reading the address on individual packets and accordingly routing the electrical signal.
A hub is a simple device which is placed in the center of a star topology. It is a simple, inexpensive device as it only repeats signals from all of its inputs to all of its outputs, without directing packets. For this reason, a hub causes many packet collisions, therefore the hub network is less efficient than a switch and works slower.
A switch directs packets from its inputs to the appropriate outputs, preventing packet collisions. Switch networks are more efficient than hub ne
tworks because many hub packets would be lost during normal operation, whereas, the switch prevents this problem by directing packets according to their address.3.4.4 Define the terms “standard protocol”, “data integrity” and “data security” in the context of data transmission across a network.
Standard Protocol refers to the set of rules that data has to follow in order to be transmitted over a network.Data Integrity refers to ensuring that the data does not change accidentally due to interference or other causes, or is lost whilst being transferred over a network.
Data Security ensures privacy of data being transmitted over the network. Encryption is a very effective method of ensuring data security.
3.4.5 Explain the software involved in networking.
In order for a PC to connect to the internet from home it is necessary to have loaded system software that enables the PC to receive and transmit data via the modem, which is in turn connected to a p
hone line.In order for a PC to connect to a LAN it needs to have the appropriate communications client software loaded.Communications software deals with protocols and data security, both for LANs and WANs and handles the need for both integrity and security of data3.4.6 Describe suitable methods to ensure data integrity in the transmission of data.
Parity checks
Checksum (BCC - Block Character Check)
Error Correction
When errors in transmission are deteced they need to be corrected. The most common type of error correction is ARQ (automatic repeat request), re-sending continues until correct communication is ach
ieved. Some codes allow a small number of corrupt bits to be corrected without retransmission ( forward error correction ).This shows that parity checks can be applied to each character, as we have seen, but also the same bit from a number of characters can also be checked.
The errors in parity intersect at the incorrect bit and it can be "flipped" to achieve correction.
3.4.7 Describe suitable methods to ensure data security.
Data security is concerned with preventing unauthorised access.User login
This requires you to enter a login and password and is the main form of network security. Passwords should be set sensibly and at a regular time interval. Passwords should not be associated with the user and should be a random combination of letters and digits. Passwords are stored on the computer but are stored in encrypted format so that if they are located they cannot be read.Data encryption
Another major security problem is the interception of data transmissions by an unauthorised third party. In order to avoid this, data is ecrypted when transmitted. This basically means that the data is scrambled at transmit time I.E. encrypted and then de-encrypted when it is received. If the data transmission is intercepted after encryption, it cannot be de-encrypted without the use of an encryption key.Permission
As well as passwords to enable users to login, each user also has a set of permissions associated with their logon name or group. Some users, administrators or super-users, can look in any data file, change user passwords and delete any file on the system. Ordinary users can only access their own files and use specified resources such as printers and CD burners.Firewall
A firewall is a device, or a piece of software that is placed between your computer and the rest of the network (where the hackers are). A firewall blocks unauthorised connections from being made to your computer or LAN. Normal data is allowed through the firewall (e.g. e-mails or web pages) but all other data is blocked.3.4.8 Discuss the need for speed in data transmission, and how speed can be enhanced.
There is a need for speed because data transmission has to be efficient and fast; if the bandwidth reaches its limit it can overload and it'll become impossible to transmit data correctly.You can assure speed in data transmission by compressing data. There are two types of data compression:
Youtube Video Explaining Lossy and Lossless Compression in Images:
3.4.9 Discuss networking applications and the implications of networking for organizations, including internal communications, electronic mail, e-commerce, conferencing and distributed processing.
Networks allow different computers to access the same hardware, like a printer; it can also share programs, data, internet and intranet. All this can benefit the organizations economically and interactively, because by installing a network in an organization, less hardware will be needed and everyone can do their work in a more organized way.Internal communications: Networks allow the sharing of data without physical contact; Electronic mail is the most commonly used to communicate in networks because it allows people to share files and message each other quickly.
E-commerce:
Conferencing: is when two or more people communicate with each other in real time, using services like Skype or Messenger (video conferencing); this allows them to have conferences without actually being in the same place.
Distributed processing: is when a task is distributed between different computers within a network, to make it quicker to process.
Best content in StJulians_ComputerScience | Diigo - Groups